package org.apache.lucene.analysis.ru;


/**
 * RussianCharsets class contains encodings schemes (charsets) and toLowerCase() method implementation
 * for russian characters in Unicode, KOI8 and CP1252.
 * Each encoding scheme contains lowercase (positions 0-31) and uppercase (position 32-63) characters.
 * One should be able to add other encoding schemes (like ISO-8859-5 or customized) by adding a new charset
 * and adding logic to toLowerCase() method for that charset.
 *
 * @author  Boris Okner, b.okner@rogers.com
 * @version $Id: RussianCharsets.java,v 1.3 2004/03/29 22:48:01 cutting Exp $
 */
public class RussianCharsets
{
    // Unicode Russian charset (lowercase letters only)
    public static char[] UnicodeRussian = {
        '\u0430',
        '\u0431',
        '\u0432',
        '\u0433',
        '\u0434',
        '\u0435',
        '\u0436',
        '\u0437',
        '\u0438',
        '\u0439',
        '\u043A',
        '\u043B',
        '\u043C',
        '\u043D',
        '\u043E',
        '\u043F',
        '\u0440',
        '\u0441',
        '\u0442',
        '\u0443',
        '\u0444',
        '\u0445',
        '\u0446',
        '\u0447',
        '\u0448',
        '\u0449',
        '\u044A',
        '\u044B',
        '\u044C',
        '\u044D',
        '\u044E',
        '\u044F',
        // upper case
        '\u0410',
        '\u0411',
        '\u0412',
        '\u0413',
        '\u0414',
        '\u0415',
        '\u0416',
        '\u0417',
        '\u0418',
        '\u0419',
        '\u041A',
        '\u041B',
        '\u041C',
        '\u041D',
        '\u041E',
        '\u041F',
        '\u0420',
        '\u0421',
        '\u0422',
        '\u0423',
        '\u0424',
        '\u0425',
        '\u0426',
        '\u0427',
        '\u0428',
        '\u0429',
        '\u042A',
        '\u042B',
        '\u042C',
        '\u042D',
        '\u042E',
        '\u042F'
    };

    // KOI8 charset
    public static char[] KOI8 = {
        0xc1,
        0xc2,
        0xd7,
        0xc7,
        0xc4,
        0xc5,
        0xd6,
        0xda,
        0xc9,
        0xca,
        0xcb,
        0xcc,
        0xcd,
        0xce,
        0xcf,
        0xd0,
        0xd2,
        0xd3,
        0xd4,
        0xd5,
        0xc6,
        0xc8,
        0xc3,
        0xde,
        0xdb,
        0xdd,
        0xdf,
        0xd9,
        0xd8,
        0xdc,
        0xc0,
        0xd1,
        // upper case
        0xe1,
        0xe2,
        0xf7,
        0xe7,
        0xe4,
        0xe5,
        0xf6,
        0xfa,
        0xe9,
        0xea,
        0xeb,
        0xec,
        0xed,
        0xee,
        0xef,
        0xf0,
        0xf2,
        0xf3,
        0xf4,
        0xf5,
        0xe6,
        0xe8,
        0xe3,
        0xfe,
        0xfb,
        0xfd,
        0xff,
        0xf9,
        0xf8,
        0xfc,
        0xe0,
        0xf1
    };

    // CP1251 eharset
    public static char[] CP1251 = {
        0xE0,
        0xE1,
        0xE2,
        0xE3,
        0xE4,
        0xE5,
        0xE6,
        0xE7,
        0xE8,
        0xE9,
        0xEA,
        0xEB,
        0xEC,
        0xED,
        0xEE,
        0xEF,
        0xF0,
        0xF1,
        0xF2,
        0xF3,
        0xF4,
        0xF5,
        0xF6,
        0xF7,
        0xF8,
        0xF9,
        0xFA,
        0xFB,
        0xFC,
        0xFD,
        0xFE,
        0xFF,
        // upper case
        0xC0,
        0xC1,
        0xC2,
        0xC3,
        0xC4,
        0xC5,
        0xC6,
        0xC7,
        0xC8,
        0xC9,
        0xCA,
        0xCB,
        0xCC,
        0xCD,
        0xCE,
        0xCF,
        0xD0,
        0xD1,
        0xD2,
        0xD3,
        0xD4,
        0xD5,
        0xD6,
        0xD7,
        0xD8,
        0xD9,
        0xDA,
        0xDB,
        0xDC,
        0xDD,
        0xDE,
        0xDF
    };

    public static char toLowerCase(char letter, char[] charset)
    {
        if (charset == UnicodeRussian)
        {
            if (letter >= '\u0430' && letter <= '\u044F')
            {
                return letter;
            }
            if (letter >= '\u0410' && letter <= '\u042F')
            {
                return (char) (letter + 32);
            }
        }

        if (charset == KOI8)
        {
            if (letter >= 0xe0 && letter <= 0xff)
            {
                return (char) (letter - 32);
            }
            if (letter >= 0xc0 && letter <= 0xdf)
            {
                return letter;
            }

        }

        if (charset == CP1251)
        {
            if (letter >= 0xC0 && letter <= 0xDF)
            {
                return (char) (letter + 32);
            }
            if (letter >= 0xE0 && letter <= 0xFF)
            {
                return letter;
            }

        }

        return Character.toLowerCase(letter);
    }
}
